One of us (Paul Lastavec) has wide experience in the timber industry and, becoming concerned with the rapidly increasing costs of conventional sawmills where an expensive saw blade can easily be destroyed, considered lasers as an alternative.
Being totally discouraged by the capabilities of laser cutting systems produced to 1985 he made an approach to the Australian Department of Industry, Technology and Commerce who directed him to the co-inventor, (JLH) who was developing scalable phased-array lasers whose operating characteristics had been classified by the United States Patent Office in 1984 and remain classified at this time.
It was considered to be a simpler task to destroy a log at a distance of a few meters than an intercontinental missile at a distance of a few thousand kilometers. Furthermore, much more precise laser beam manipulation was possible over distances of several meters in particular the use of the pre pulse self-focussing plasma lens to generate "hair-line" cuts in any material.
An additional advantage of the laser "hair-line" cut is the fact that the cut surfaces are automatically sealed during the cutting process so that body moisture is trapped within the cut sections of the logs eliminating the need for expensive drying processes.
Although the width of the laser induced "hair-line" cut is of the order of 10.sup.-4 centimeters, a typical log can be one meter in diameter and up to 30 meters in length. This means that the volume of material that needs to be ablated is about 30 cubic centimeters, no mean task. However, we need only compress this amount of material sideways in total distance of less than 5.times.10.sup.-5 centimeters over the whole cut surfaces of the log. There is no need to annihilate 30 cubic centimeters of material. All that is needed of a 10 megajoule laser is the planar creation of a "hair-line" cut whose area is up to 300,000 square centimeters. We contemplate a laser output power up to 10.sup.17 watts.